Project Summary/Abstract Having Alzheimer's disease or a related dementia, being ambulatory, and awakening in the night constitute a recipe for a dangerous fall. Add a lighting system that promotes postural stability, and the fall may be avoided. Falls are the primary cause of fatal and non-fatal injuries among persons 65 years of age and older. Dementia is a primary risk factors for falls, and assisted living (AL) communities are the primary provider of residential care for older adults with dementia, making AL a critical setting in which to reduce falls. Forty-two percent of the more than 835,000 AL residents across the U.S. have moderate or severe cognitive impairment or dementia, 80% of whom are ambulatory and more than one-third of whom experience a fall in a six month period, putting them among the 15% of AL residents who suffer a hip fracture or other serious fall-related injury each year. Falls are responsible for one-third of all hospitalizations of AL residents, and the resulting injuries may lead to a cascade of events including worsening function, nursing home transfer, and death. A significant number of these falls occur during evening hours and when AL staff are not present, thereby limiting their ability to intervene. However, the cause of many of these falls -- impaired nighttime vision and related postural instability -- suggests a promising avenue for intervention. Specifically, an intervention that does not require staff effort, and that targets orientation and postural stability in the evening and night when lighting is poor and residents may not be fully awake, has great potential to reduce falls in AL. The proposed study represents the first test of a lighting system to address falls in AL. If successful, such a system could also be used in nursing homes and private residences. Prior to conducting a definitive trial of the effectiveness of the lighting system, more information is needed regarding implementation and effect size. Therefore, this exploratory multi-site randomized crossover trial, to be conducted in four AL communities, will test a novel lighting system intended to promote postural stability by providing horizontal and vertical visual cues, to (1) individualize, implement, and monitor the operation of the lighting system; (2) determine the feasibility of conducting a definitive trial of the lighting system; and (3) examine outcomes of the lighting system. The results of this project will inform the methods and expected effect and sample size for a more definitive R01 proposal. Results also will be shared with research and provider organizations to inform ongoing efforts to reduce falls among residents with Alzheimer's disease and related dementias in AL.